The present invention concerns a method and a device for transitioning between an image of a first video sequence and an image of a second video sequence. The invention further relates to a method and device for transmitting video sequences.
Embodiments of the present invention may be applied in the context of remote browsing of video sequences by a client via of a network such as the Internet. Some video data provider systems provide video data of video sequences with region of interest (ROI) functionalities. Such systems typically comprise a video server associated with a database of correlated video sequences. One such video sequence may comprise an overview video sequence with clickable subparts (ROIs). Other video sequences in the database may correspond to one or more regions of interest of the first video sequence in a higher resolution, for example, also referred to as zoomed versions. Such videos sequences are often referred to as ROI videos. The video server provides the different video sequences with metadata that may be used to access the regions of interest at the client side.
The regions of interest may be predetermined, for instance, by the user or by an administrator of the video sequence database. In some cases the regions of interest move within the overview video sequence to follow moving objects of a recorded scene. A client receiving the data can superimpose regions of interest over the display of the overview video sequence. When the user selects one of the regions of interest, the client sends a request to obtain the corresponding ROI video sequence. Media Fragment URI for example may be employed to retrieve the ROI video sequence from the current time of the overview video sequence. The server stops the streaming of the overview video sequence and starts sending the requested ROI video from the requested start time.
On the client side, the browser switches from playing the overview video sequence to playing the ROI video sequence once it has received the ROI video sequence by performing a transition (typically a zoom-in transition). Then, in response to a second user click, the client can send a request to the server to request a media fragment of the overview video sequence from the current time to the end of the file or video sequence. The server then stops the transmission of the ROI video and starts streaming of the overview video sequence. The browser performs a transition (typically a zoom-out transition) once the overview video data is received.
Due to latency in transmission, the availability of video data is not guaranteed immediately after the client has requested it. The transition between the two video sequences cannot be performed immediately since video data of the second video sequence is not received instantaneously after the client's request. Traditionally it was necessary to wait for video data of the second video sequence to be received before performing the transition. The main disadvantage of such a method is that when the transmission delay is close to or even exceeds one second, the transition does not occur as soon as the user requests it.